Transcript Document

Contact lenses were
thought of as early as
1508 when Leonardo da
Vinci sketched and
described several forms of
them.
Contact lenses are a
changing area of
optometry with new lenses
being constantly
developed
Refractive errors are
corrected by contact
lenses, which are placed
directly on the cornea
pupil
cornea
iris
sclera
Lid
margin
conjunctiva
Normal focus
Short sightedness
(Myopia)
• Distance vision blurry, near usually OK.
Short-sighted
focus
Short-sighted
correction
Long-sightedness
(Hyperopia)
• Difficulty seeing clearly and comfortably
up close.
Long-sighted
focus
Long-sighted
correction
Astigmatism
• Irregular curvature of the eye (shaped
more like a football than a basketball)
• Light in different planes focuses at
different points
A
90
B
180
There are many types of
contact lenses
 RGP lenses
 Soft lenses
 Disposable or non-disposable
 Coloured or clear
 Spherical or toric
 Extended wear
 Multifocal
RGP lenses (rigid gas
permeable)
 Smaller than size of cornea
 May be less comfortable than soft
lenses initially
 Very effective in correcting astigmatism
RGP contact lens
Soft lenses
 Most commonly used (90%)
 Made from hydrogel plastic material
containing water
 Are 1-2mm larger than cornea
 Easy to adapt to
Soft contact lens
Spherical lenses
 Correct short or long-sightedness
 Cheapest, most comfortable lenses
 Easy to get in disposable form
Toric lenses
 Correct astigmatism
 Lens is specially weighted to conform
to irregular cornea
 More expensive than spherical
 Some are available in disposable
Disposable lenses
 Daily, two-weekly or monthly
replacement
 Very simple cleaning (no cleaning
for daily)
 Latest designs and materials
 Very popular
Coloured lenses
 Handling tint
 Useful when inserting or removing
 Enhancing tint
 Makes light coloured eyes more vivid
 Opaque tint
 Can change brown eyes to blue
Extended wear lenses
 New technology
 Made from silicone material which
transmits oxygen well
 Can wear for up to thirty days without
removing
 Will not suit all people – your optometrist
will advise
Multifocal contact lenses
 Can wear one reading lens, one distance
 Can have dual focus lenses
 New technology – slightly more expensive
 Available as a disposable lens
Advantages of contact
lenses over glasses
 Better field of view
 No fogging up
 No one has to know you have refractive
error
 No frames – eg, useful for sport
 Sometimes the vision is better
Hygiene is extremely
important with contact
lenses
 Always wash your hands before
touching lenses
 If lenses are not clean, bacteria can stick
to them
 A tiny scratch on the eye can
get infected
If you have a sore, red eye
take your lenses out and
go to see your optometrist
ASAP
If properly looked after,
the chance of having an
infection with contact
lenses is extremely low
Consultations for contact
lenses
 Contact lenses need to be fitted to each
individual eye
 Several tests are required for:
 measuring and trying the lenses
 teaching insertion and removal
 after care
 Your optometrist can advise you about the
tests are required
Optometrists
 Detect and diagnose
problems with eye health
 Prescribe glasses or contact
lenses, if required
 Diagnose and treat problems
with focusing
Optometrists
 Are university educated and regularly
undertake continuing professional
education
 No referral is required
To find an optometrist
 Yellow pages
 NZ Association of Optometrists
www.nzao.co.nz
0800 439 322